首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   26899篇
  免费   2757篇
  国内免费   2035篇
耳鼻咽喉   165篇
儿科学   201篇
妇产科学   244篇
基础医学   3174篇
口腔科学   414篇
临床医学   3717篇
内科学   3822篇
皮肤病学   248篇
神经病学   1462篇
特种医学   1225篇
外国民族医学   18篇
外科学   2852篇
综合类   4796篇
现状与发展   12篇
一般理论   4篇
预防医学   1900篇
眼科学   672篇
药学   2795篇
  35篇
中国医学   1707篇
肿瘤学   2228篇
  2024年   111篇
  2023年   505篇
  2022年   1343篇
  2021年   1667篇
  2020年   1270篇
  2019年   1108篇
  2018年   1058篇
  2017年   956篇
  2016年   915篇
  2015年   1264篇
  2014年   1653篇
  2013年   1461篇
  2012年   2098篇
  2011年   2219篇
  2010年   1385篇
  2009年   1076篇
  2008年   1300篇
  2007年   1312篇
  2006年   1271篇
  2005年   1209篇
  2004年   787篇
  2003年   837篇
  2002年   764篇
  2001年   607篇
  2000年   596篇
  1999年   587篇
  1998年   380篇
  1997年   380篇
  1996年   247篇
  1995年   255篇
  1994年   223篇
  1993年   148篇
  1992年   146篇
  1991年   142篇
  1990年   81篇
  1989年   70篇
  1988年   82篇
  1987年   61篇
  1986年   33篇
  1985年   23篇
  1984年   21篇
  1983年   10篇
  1982年   4篇
  1981年   9篇
  1980年   2篇
  1979年   7篇
  1978年   3篇
  1972年   2篇
  1970年   1篇
  1968年   1篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
AIM OF THE STUDY: Our previous results have shown one species of parasitic loranthus (Taxillus chinensis (DC.) Dancer) exhibits potent inhibition on fatty acid synthase (FAS) that is proposed to be a potential therapeutic target for treatment of obesity. However, the medicinal parasitic loranthus come from tens of plants of two families, the Loranthaceae and the Viscaceae. This study was carried out to figure out whether these parasitic loranthus from the two families have similar inhibitory ability on FAS, and whether the parasitic loranthus with potent inhibitory ability on FAS significantly reduce body weight of animal. MATERIALS AND METHODS: CD-1 mice were used to test the effects of samples on their body weight and food intake in 20 days. The reversible and irreversible inhibition on FAS was assayed to study the inhibitory ability of sixteen different medicinal plants from these two families, which were collected in nature. RESULTS: The reversible inhibitory ability of the extracts from the Loranthaceae was nearly 400-fold stronger than that from the Viscaceae. The species from the genus Taxillus Tieghem showed the best effect on FAS in both reversible and irreversible inhibition. Moreover, the difference in host plants did not affect markedly on the inhibitory ability of parasitic loranthus. The medicinal herb with high inhibitory ability on FAS significantly reduced the body weight and food intake of mice by oral administration. CONCLUSIONS: The medicinal herbs from the family Loranthaceae, rather than those from the family Viscaceae, should be suitable to apply as botanical sources of parasitic loranthus for weight control. The herbs from genus Taxillus Tieghem are the best.  相似文献   
92.
不完全型P450 17α酶缺乏症六例报道及分析   总被引:1,自引:0,他引:1  
目的 探讨不完全型P45017α酶(17α羟化爵每/17,20裂解酶)缺乏症(17OHD)的临床特征、鉴别诊断和处理方法。方法 回顾性分析北京协和医院6例不完全型17OHD的临床特征,并通过文献复习讨论该病的发病机制和典型的临床特征。结果 6例中4例为46,XX不完全型17OHD患者,其临床特征包括女性表型、不同程度的乳房发育、阴毛少、月经稀发或继发闭经、反复发作的卵巢囊肿、性腺功能低下伴持续性血清孕酮和(或)17α羟孕酮水平升高、合并或不合并低钾性高血压;另2例为46,XY不完全型17OHD患者,伴有不同程度的外生殖器性别不清和低钾性高血压。结论 不完全型17OHD是一种极为罕见的先天性甾体合成酶缺乏,临床上出现月经异常、性发育幼稚、反复发作的卵巢囊肿或外生殖器性别不清时应考虑此病。  相似文献   
93.
Tumor lymphangiogenesis and lymphangiogenic growth factors   总被引:2,自引:0,他引:2  
Recent studies have revealed that malignant tumors can actively induce the formation of new lymphatic vessels and metastasize through the lymphatic system. Tumor-induced lymphangiogenesis driven by tumors expressed lymphangiogenic growth factors such as VEGF family, fibroblast growth factor 2 (FGF-2), angiopoietin-1 (Ang-1), angiopoietin-2 (Ang-2), and platelet-derived growth factors (PDGFs) is correlated with lymph node metastasis in experimental cancer models and in several types of human cancers. Tumor- induced lymphangiogenesis has now been firmly established as a novel mechanism for cancer progression and lymph node metastasis. Recent studies indicate that blockade of the lymphangiogenic growth factors pathway inhibits tumor spread to lymph nodes and likely beyond. The potential effects of most of these newly identified lymphatic growth factors on tumor-induced lymphangiogenesis and lymph node metastasis remain to be further investigated. A number of questions remain to be answered concerning the potential efficacy of targeting at tumor-induced lymphangiogenesis for inhibiting tumor spread to lymph nodes.  相似文献   
94.
目的 探讨巴曲酶和尿激酶联合使用能否减少颅内出血并发症。方法 采用大鼠大脑中动脉闭塞(MCAO)线栓法模型,将大鼠随机分为对照组、假手术组、单独或联合使用巴曲酶和尿激酶组,共9组,每组15只。观察颅内出血、脑梗塞体积和神经功能缺损情况。结果 尿激酶5000U/kg组有5只颅内出血。巴曲酶5BU/kg(2h) 尿激酶5000U/kg(2h)组有4只颅内出血,巴曲酶5BU/kg(1h) 尿激酶5000U/kg(2h)组有1只颅内出血。巴曲酶5BU/kg(2h)组、巴曲酶10BU/kg(2h) 尿激酶2500U/kg(2h)组可缩小梗塞体积比。各组神经功能缺损无明显差异。结论 5000U/kg尿激酶造成颅内出血增加。单独使用巴曲酶颅内出血不增加,巴曲酶和尿激酶联合应用不增加颅内出血。  相似文献   
95.
TiMoN coatings with different Mo contents on a SS316L substrate are deposited by using closed field unbalanced magnetron sputtering ion plating (CFUMSIP) technology to enhance the corrosion resistance and durability of stainless steel (SS) bipolar plates (BPs) in proton exchange membrane fuel cell (PEMFC) during the start-up/shut-down process. The electrochemical test results illustrate that TiMoN-4A coating has extremely good corrosion resistance compared to other coatings. The potentiostat polarization (+0.6 VSCE) tests indicate that the corrosion current density (Icorr) of TiMoN-4A coating is 5.22 × 10−7A cm−2, which meets the department of energy 2020 targets (DOE, ≤1 × 10−6 A cm−2). Otherwise, TiMoN-4A coating also exhibits the best corrosion resistance and stability in potentiostatic polarization, electrochemical impedance spectroscopy (EIS), and high potential (+1.2VSCE) polarization tests. The interfacial contact resistance (ICR) measurement results show that TiMoN-4A coating has the minimum ICR of 9.19 mΩ·cm2, which meets the DOE 2020 targets (≤10 mΩ·cm2).  相似文献   
96.
Friction stir additive manufacturing (FSAM) can be potentially used for fabricating high-performance components owing to its advantages of solid-state processing. However, the inhomogeneous microstructures and mechanical properties of the build attributed to the complex process involving restirring and reheating deserve attention. This study is based on the previous research of the underwater FSAMed 7A04 aluminum alloy and adopts a quasi in situ experimental method, i.e., after each pass of the underwater FSAM, samples were taken from the build for microstructural observation to investigate the restirring and reheating effects on microstructural evolution during the underwater FSAM. Fine-grain microstructures were formed in the stir zone during the single-pass underwater FSAM. After restirring, the grain size at the bottom of the overlapping region decreased from 1.97 to 0.87 μm, the recrystallization degree reduced from 74.0% to 29.8%, and the initial random texture transformed into a strong shear texture composed of the C {110}<11¯0>. After reheating, static recrystallization occurred in the regions close to the new additive zones, increasing the grain size and recrystallization degree. This study not only revealed the microstructural evolution during the underwater FSAM but also provided a guideline for further optimization of the mechanical properties of the Al–Zn–Mg–Cu alloy build.  相似文献   
97.
目的 分析晚期肺癌化疗患者家庭韧性的现状及其与希望水平、生活质量的相关性。方法 选取2020年8月至11月在某省级三级甲等肿瘤专科医院就诊的144例晚期肺癌化疗患者,采用一般资料调查表、家庭韧性评定量表中文简化版、Herth希望量表以及肺癌治疗功能评定量表对其进行调查。结果 晚期肺癌化疗患者家庭韧性总分为(89.90±8.11)分、希望水平总分为(31.89±4.01)分、生活质量总分为(88.85±11.69)分。工作状况、家庭人均月收入、希望水平及生活质量是晚期肺癌化疗患者家庭韧性的影响因素(P<0.01或P<0.05)。结论 晚期肺癌化疗患者家庭韧性、希望水平处于中等水平,生活质量较低,均有待提高。临床医护工作者应加强对患者家庭经济情况的关注,积极探索提高其希望水平及生活质量的护理干预措施,从而提高家庭韧性水平。  相似文献   
98.
Acne is a chronic inflammatory skin disease of the sebaceous glands of the hair follicles, caused by a variety of factors and tends to recur, causing skin damage and psychological stress to patients. Blue light (415nm) is a popular physical therapy for acne, however, studies on the effects of blue light on skin surface lipids (SSL) have not been exhaustively reported. So, we want to investigate the difference in SSL before and after acne treatment with blue light and to reveal the potential mechanism of acne treatment with blue light from the lipid level. SSL samples were collected and physiological indicators (moisture content, transepidermal water loss (TEWL), sebum content and pH) were measured. By using ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) with multivariate data analysis methods to obtain specific information on the lipid composition. Analysis of the physiological index data showed a significant increase in moisture content (p = 0.042), pH (p = 0.000) and a significant decrease in sebum content(p = 0.008) in the after treatment area (AT group), while there was no significant change in TEWL values. A total of 2398 lipids were detected by lipidomics analysis and 25 differential lipids were screened. Triradylglycerols (TGs), isoprenoids and hopanoids being the potential differential lipids. Among the lipids associated with the skin barrier, only monounsaturated fatty acids (MUFA) (p = 0.045) were significantly increased. This study revealed significant changes in SSL after blue light treatment for acne, suggesting that blue light exposure may cause changes in the relative lipid content and redistribution of lipid components, and that whether it damages the skin barrier requires further study.  相似文献   
99.
Despite the well-known benefits of breastfeeding and the World Health Organization’s breastfeeding recommendations for COVID-19 infected mothers, whether these mothers should be encouraged to breastfeed is under debate due to concern about the risk of virus transmission and lack of evidence of breastmilk’s protective effects against the virus. Here, we provide a molecular basis for the breastfeeding recommendation through mass spectrometry (MS)-based proteomics and glycosylation analysis of immune-related proteins in both colostrum and mature breastmilk collected from COVID-19 patients and healthy donors. The total protein amounts in the COVID-19 colostrum group were significantly higher than in the control group. While casein proteins in COVID-19 colostrum exhibited significantly lower abundances, immune-related proteins, especially whey proteins with antiviral properties against SARS-CoV-2, were upregulated. These proteins were detected with unique site-specific glycan structures and improved glycosylation diversity that are beneficial for recognizing epitopes and blocking viral entry. Such adaptive differences in milk from COVID-19 mothers tended to fade in mature milk from the same mothers one month postpartum. These results suggest that feeding infants colostrum from COVID-19 mothers confers both nutritional and immune benefits, and provide molecular-level insights that aid breastmilk feeding decisions in cases of active infection.  相似文献   
100.
BackgroundMultiple assessment tools are used in arthroscopic training and play an important role in feedback. However, it is not fully recognized as to the standard way to apply these tools. Our study aimed to investigate the use of assessment tools in arthroscopic training and determine whether there is an optimal way to apply various assessment tools in arthroscopic training.MethodsA search was performed using PubMed, Embase and Cochrane Library electronic databases for articles published in English from January 2000 to July 2021. Eligible for inclusion were primary research articles related to using assessment tools for the evaluation of arthroscopic skills and training environments. Studies that focussed only on therapeutic cases, did not report outcome measures of technical skills, or did not mention arthroscopic skills training were excluded.ResultsA total of 28 studies were included for review. Multiple assessment tools were used in arthroscopic training. The most common objective metric was completion time, reported in 21 studies. Technical parameters based on simulator or external equipment, such as instrument path length, hand movement, visual parameters and injury, were also widely used. Subjective assessment tools included checklists and global rating scales (GRS). Among these, the most commonly used GRS was the Arthroscopic Surgical Skill Evaluation Tool (ASSET). Most of the studies combined objective metrics and subjective assessment scales in the evaluation of arthroscopic skill trainingConclusionsOverall, both subjective and objective assessment tools can be used as feedback for basic arthroscopic skill training, but there are still differences in the frequency of application in different contexts. Despite this, combined use of subjective and objective assessment tools can be applied to more situations and skills and can be the optimal way for assessment.Level of EvidenceLevel III, systematic review of level I to III studies.

Key messages

  • Both subjective and objective assessment tools can be used as feedback for basic arthroscopic skill training.
  • Combined use of subjective and objective assessment tools can be applied to more situations and skills and can be the optimal way for assessment.
  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号